sync: Specialize functions that fetch type root

sync/engine/apply_control_data_updates.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sync/engine/apply_control_data_updates.h"
 
 #include "base/metrics/histogram.h"
 #include "sync/engine/conflict_resolver.h"
 #include "sync/engine/conflict_util.h"
 #include "sync/engine/syncer_util.h"
 #include "sync/syncable/directory.h"
 #include "sync/syncable/mutable_entry.h"
 #include "sync/syncable/nigori_handler.h"
 #include "sync/syncable/nigori_util.h"
 #include "sync/syncable/syncable_write_transaction.h"
 #include "sync/util/cryptographer.h"
 
 namespace syncer {
 
-using syncable::GET_BY_SERVER_TAG;
+using syncable::GET_TYPE_ROOT;
 using syncable::IS_UNAPPLIED_UPDATE;
 using syncable::IS_UNSYNCED;
 using syncable::SERVER_SPECIFICS;
 using syncable::SPECIFICS;
 using syncable::SYNCER;
 
 void ApplyControlDataUpdates(syncable::Directory* dir) {
   syncable::WriteTransaction trans(FROM_HERE, SYNCER, dir);
 
   std::vector<int64> handles;
   dir->GetUnappliedUpdateMetaHandles(
       &trans, ToFullModelTypeSet(ControlTypes()), &handles);
 
   // First, go through and manually apply any new top level datatype nodes (so
   // that we don't have to worry about hitting a CONFLICT_HIERARCHY with an
   // entry because we haven't applied its parent yet).
   // TODO(sync): if at some point we support control datatypes with actual
   // hierarchies we'll need to revisit this logic.
   ModelTypeSet control_types = ControlTypes();
   for (ModelTypeSet::Iterator iter = control_types.First(); iter.Good();
        iter.Inc()) {
-    syncable::MutableEntry entry(&trans,
-                                 syncable::GET_BY_SERVER_TAG,
-                                 ModelTypeToRootTag(iter.Get()));
+    syncable::MutableEntry entry(&trans, syncable::GET_TYPE_ROOT, iter.Get());
     if (!entry.good())
       continue;
     if (!entry.GetIsUnappliedUpdate())
       continue;
 
     ModelType type = entry.GetServerModelType();
     if (type == NIGORI) {
       // Nigori node applications never fail.
       ApplyNigoriUpdate(&trans,
                         &entry,
@@ skipping 157 matching lines @@
                               ConflictResolver::OVERWRITE_LOCAL,
                               ConflictResolver::CONFLICT_RESOLUTION_SIZE);
   }
 
   UpdateAttemptResponse response = AttemptToUpdateEntry(
       trans, entry, cryptographer);
   DCHECK_EQ(SUCCESS, response);
 }
 
 }  // namespace syncer